Saccharomyces cerevisiae can utilize allantoin by virtue of its ability to degrade the compound to ammonia glyoxylate and CO2. In view of our previous results that allophanate, the last intermediate of the pathway, is needed for induction to ocur, we are studying the induction process physiologically using antifungal drugs of known inhibitory mechanisms and genetically by attempting to isolate mutants which are defective in the control elements of this system.